BACKGROUND: Lower extremity muscle strength tests are commonly used to screen for injury risk in professional soccer. However, there is limited evidence on the ability of such tests in predicting future injuries. PURPOSE: To examine the association between hip and thigh muscle strength and the risk of lower extremity injuries in professional male soccer players. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Professional male soccer players from 14 teams in Qatar underwent a comprehensive strength assessment at the beginning of the 2013/2014 and 2014/2015 seasons...

OBJECTIVES: Studies comparing the effects of fatigue between men and women after anterior cruciate ligament (ACL) reconstruction are lacking. The purpose of this study was to compare the effects of muscle fatigue on trunk, pelvis and lower limb kinematics and on lower limb muscle activation between male and female athletes who underwent ACL reconstruction. DESIGN: Cross-sectional study. SETTING: Laboratory setting. PARTICIPANTS: Fourteen recreational athletes (7 males and 7 females) with unilateral ACL reconstruction participated of this study...

PURPOSE: This 3-year prospective study assessed risk factors for noncontact anterior cruciate ligament (ACL) injuries in female Japanese high school basketball players. Players suffering noncontact ACL injuries were assumed to demonstrate poorer hip abductor, knee flexor, and knee extensor muscle strength, as well as static balance, than those without injuries. METHODS: One hundred and ninety-five new female high school basketball players underwent baseline examinations for various parameters during their first year of high school...

Turnout is a central element of classical ballet which involves sustained external rotation of the lower limbs during dance movements. Lower leg and foot compensation mechanisms which are often used to increase turnout have been attributed to the high incidence of lower limb injury in dancers. Evaluation of dancers' leg posture is needed to provide insight into the lower limb kinematic strategies used to achieve turnout. The primary purpose of this study was to use 3D kinematic analyses to determine the lower leg and foot compensations that are incorporated by female university dancers to accentuate their turnout...

The internal knee abduction moment (KAM) in osteoarthritis is reduced by increased lateral trunk lean (TL). Mechanistically, this occurs as the Centre of Mass (COM) moves further over the stance leg. Since the size of the base of support constrains the COM, an associated increase in step width (SW) would be expected to maintain stability. This study tested the effects of TL on SW and KAM in healthy participants (n = 21) who performed normal and 6° TL walks. The latter was controlled via audio-visual biofeedback...

The Microsoft Xbox One Kinect™ (Kinect V2) contains a depth camera that can be used to manually identify anatomical landmark positions in three-dimensions independent of the standard skeletal tracking, and therefore has potential for low-cost, time-efficient three-dimensional movement analysis (3DMA). This study examined inter-session reliability and concurrent validity of the Kinect V2 for the assessment of coronal and sagittal plane kinematics for the trunk, hip and knee during single leg squats (SLS) and drop vertical jumps (DVJ)...

The aim of this study was to identify the effects of a corrective exercise program on landing ground reaction force characteristics and lower limb kinematics in older adults with genu valgus. Twenty six older male adults with genu valgus were randomized into two groups. An experimental group conducted a 14- week corrective exercise program, while a control group did not perform any exercise. The experimental group displayed lower peak vertical, peak anterior and posterior, and peak medial ground reaction force components during the post-test compared to the pre-test...

BACKGROUND: Previous studies have demonstrated increased medial stresses in knee varus alignment. Selecting a suitable treatment strategy for individuals with knee malalignment should be a priority. OBJECTIVES: We aimed to investigate the effects of a 16-week corrective exercise continuum (CEC) program on 3-D joint angles of the dominant and non-dominant lower limbs in children with genu varus during walking. METHODS: Overall, 28 male children with genu varus (age range 9-14 years) volunteered to participate in this study...

This study quantified the contributions by muscular, gravitational and inertial forces to the ground reaction force (GRF) and external knee adduction moment (EKAM) for knee osteoarthritis (OA) patients and controls walking at similar speeds. Gait data for 39 varus mal-aligned medial knee OA patients and 15 controls were input into musculoskeletal models to calculate the contributions of individual muscles and gravity to the fore-aft (progression), vertical (support), and mediolateral (balance) GRF, and the EKAM...

BACKGROUND: Aberrant walking-gait and jump-landing biomechanics may influence the development of post-traumatic osteoarthritis and increase the risk of a second anterior cruciate ligament injury, respectively. It remains unknown if individuals who demonstrate altered walking-gait biomechanics demonstrate similar altered biomechanics during jump-landing. Our aim was to determine associations in peak knee biomechanics and limb-symmetry indices between walking-gait and jump-landing tasks in individuals with a unilateral anterior cruciate ligament reconstruction...

BACKGROUND: Anterior cruciate ligament (ACL) injuries are prevalent in contact sports that feature cutting and pivoting, such as American football. These injuries typically require surgical treatment, can result in significant missed time from competition, and may have deleterious long-term effects on an athlete's playing career and health. While the majority of ACL tears in other sports have been shown to occur from a noncontact mechanism, it stands to reason that a significant number of ACL tears in American football would occur after contact, given the nature of the sport...

INTRODUCTION: Osteoarthritis mainly affects weight-bearing joints such as the hip and knee and is the most common form of arthritis. Greater muscle atrophy with fatty infiltration of gluteal muscles and decreased hip abduction strength has previously been identified with increasing severity of radiological hip OA. However, it is well documented that radiographic findings of OA do not always correlate with clinical severity. The aim of this secondary analysis was to examine whether atrophy and strength of gluteus maximus (GMax), medius (GMed), minimus (GMin), and tensor fascia lata (TFL) is associated with the clinical severity of OA...

BACKGROUND: Recent studies highlight the need for understanding movement control of adjacent joints when evaluating knee function following anterior cruciate ligament (ACL) injury. However, while short-term adaptations to lower-extremity joint coupling have been studied, little is known about any potential long-term adaptations in neuromuscular control displayed by ACL-injured individuals. The aim of our study was to determine whether coordination variability of the hip-knee joint couplings during the one-leg hop is altered about 20 years after injury in two ACL-injured groups compared to healthy knee controls...

BACKGROUND: Outdoor falls in community-dwelling older adults are often triggered by uneven pedestrian walkways. It remains unclear how older adults adapt to uneven surfaces typically encountered in the outdoor built-environment and whether these adaptations are associated to age-related physiological changes. RESEARCH QUESTION: The aims of this study were to (1) compare gait parameters over uneven and flat brick walkways, (2) evaluate the differences between older and young adults for these two surfaces, and (3) assess if physiological characteristics could predict adaptations in older adults...

This study investigated the influence of an incremental exercise on bilateral asymmetry through the spatio-temporal evolution of 3D joint angular displacement, using the Normalized Symmetry Index ([Formula: see text]) and cross-correlation methods. Twelve professional cyclists performed an incremental test to exhaustion, during which motion capture was used. Results revealed a decrease in range of motion between the first and last stages for twelve of the eighteen joint rotations, with the highest impact observed for right hip flexion/extension (61...

BACKGROUND: Rigid attachment systems are one of the methods used to compensate for soft tissue artifact (STA) inherent in joint motion analyses. RESEARCH QUESTION: The goal of this study was to quantify STA of an exoskeleton design to reduce STA at the knee, and to assess the accuracy of 3D knee kinematics recorded with the exoskeleton in non-obese and obese subjects during quasi-static weight-bearing squatting activity using biplane radiography. METHODS: Nine non-obese and eight obese subjects were recruited...

PURPOSE: To examine the extent to which an ACL injury prevention programme modifies lower extremity biomechanics during single- and double-leg landing tasks in both the sagittal and frontal plane. It was hypothesized that the training programme would elicit improvements in lower extremity biomechanics, but that these improvements would be greater during a double-leg sagittal plane landing task than tasks performed on a single leg or in the frontal plane. METHODS: Ninety-seven competitive multi-directional sport athletes that competed at the middle- or high-school level were cluster randomized into intervention (n = 48, age = 15...

Unanticipated direction to cut after landing may alter the lower extremity landing biomechanics when performing landing motions. These alterations may potentially increase the risk of ACL injury. The purpose of this study was to determine if an unanticipated side-cut affects lower extremity landing biomechanics in females. Eighteen recreational female athletes participated in two blocks of testing: the first block of testing consisted of three acceptable trials of anticipated dominant limb and non-dominant limb 45-degree diagonal cutting after landing, which were performed in a counterbalanced order...